Vacuum Ultraviolet Photoionization and Photodissociation of Cyanoethylene

Photoioinzation and photodissociation of cyanoethylene are performed by using vacuum ultraviolet （VUV） photons from Hefei synchrotron radiation source and a time-of-flight mass spectrometer （TOF-MS）. The photoionization mass spectrum and the photoionization efficidency （PIE） curves of all the observed ions from cyanoethylene were measured. The appearance potentials of all ions were obtained from their PIE curves. From these data, the formation enthalpies of sorne chief ions have been evaluated, and the possible channels and their competition of dissociative photoionization have been discussed. The experimetal results show that a small stable molecule HCN is easily lost, thus the ion C₂H₂⁺ is formed, and this channel is the chief dissociative photoionization channel.